Ball Bearing


This is a vial of small bearing balls collected by the Anti-Friction Bearing Manufacturers Association for a public relations exhibit during the early 1950s that was donated to the museum in 1977. For optimum bearing performance, balls in a bearing must be perfect spheres of exactly uniform size. If not, the bearing’s load will focus on the irregular ball, leading to failure in the bearing. During the middle of the 20th century, balls were manufactured by the “cold heading” process. In cold heading a piece of cylindrical steel wire is cut and compressed by a spherical die. This forms rough balls with protrusions at the top and around the equator. The balls go into a grinder to remove these protrusions in a process called deflashing. Further heating, grinding, lapping, and cleaning leaves uniform balls ready to be added to its matching cage or raceway to make a fully assembled bearing.

Simple bearings have been used for thousands of years reducing friction on turning parts like the axles of carts. In the late 1800s and early 1900s advances in machining and production expanded bearing use in all types of machines greatly increasing their life and precision. Bearings reduce friction on turning surfaces and keep them running true. Bearings come in a variety of shapes and sizes (including ball, roller, tapered, and simple friction). Modern bearings are often set in an inner and outer ring (called a race) sometimes with cages (separators) spacing the bearings. Changes to the size, shape, alignment, race, and cage allow for bearings to be used in almost any industry—from industrial turbines and automobiles to household mixers and computer hard drives.

Location: Currently not on view

See more items in: Work and Industry: Mechanical and Civil Engineering, Industry & Manufacturing


Exhibition Location:

Data Source: National Museum of American History

Id Number: MC.336100.0107Catalog Number: 336100.0107Accession Number: 1977.0585

Object Name: Bearing Balls, Set of

Physical Description: glass (bottle material)Measurements: overall: 2 3/4 in x 3/4 in; 6.985 cm x 1.905 cm


Record Id: nmah_846675

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